Analog Devices Inc./Maxim Integrated MAX6390XS26D4+T

Overview

MAX6390XS26D4+T from Maxim Integrated is a low-power microprocessor supervisory circuit with open-drain active-low reset output, factory-set 2.63V VCC reset threshold (±2.5% over -40°C to +125°C), 1120ms VCC reset timeout, and 140ms manual reset timeout. It monitors single supply voltage in battery-powered or space-constrained embedded systems requiring guaranteed reset assertion down to VCC = 1V.

For engineers reviewing the MAX6390XS26D4+T datasheet, MAX6390XS26D4+T pinout, MAX6390XS26D4+T application, or MAX6390XS26D4+T equivalent, key selection considerations include its 4-pin SC70 package, 3μA supply current at 1.8V, internal 1.56kΩ MR pullup, and immunity to negative-going VCC transients up to 150µs at 100mV overdrive.

Technical Context

The MAX6390XS26D4+T implements a precision bandgap-based reset comparator with ±2.5% threshold accuracy across -40°C to +125°C and 60ppm/°C tempco. Its dual-timing architecture separates VCC-initiated reset (1120ms min) from manual reset (140ms min), enabling independent power-up stabilization and operator-triggered recovery.

It features an open-drain RESET output requiring external pullup, a debounced MR input with 1.56kΩ internal pullup to VCC, and guaranteed valid logic states for VCC ≥ 1V - critical for brownout resilience in portable equipment where supply rails collapse gradually.

Key Specifications

Pinout & Package

MAX6390XS26D4+T is housed in a RoHS-compliant 4-pin SC70 package (outline 21-0098, land pattern 90-0187), measuring 1.25mm × 1.25mm × 0.95mm, optimized for high-density PCB layouts in portable electronics.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar microprocessor reset applications.

Compared with MAX6326XR26D4+T and TPS3808G33DBVR, the MAX6390XS26D4+T uniquely combines precise 2.63V supervision, dual-timing independence, and MR support in a 4-pin SC70 footprint - making it optimal for compact, battery-sensitive designs needing deterministic manual intervention.

Availability

MAX6390XS26D4+T is available at Aetrix Electronics and suitable for portable medical sensors, industrial PLC I/O modules, automotive body control units, and smart energy meters requiring stable component supply with guaranteed long-term availability.

Supply support for MAX6390XS26D4+T includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Maxim Integrated (now part of Analog Devices) designs precision analog, mixed-signal, and power management ICs for demanding industrial, automotive, and computing applications.

The MAX6381–MAX6390 family delivers ultra-low-power, high-accuracy reset supervision for battery-operated and thermally harsh systems where supply rail integrity directly impacts functional safety and data reliability.

FAQ

What is the exact reset threshold voltage of the MAX6390XS26D4+T and how tightly is it specified?

The MAX6390XS26D4+T has a factory-set nominal reset threshold of 2.63V, with guaranteed tolerance of ±2.5% over the full operating temperature range (-40°C to +125°C). This specification is confirmed in the Electrical Characteristics table of the official datasheet, where VTH min = 2.56V and max = 2.69V at +25°C, and ±2.5% applies across temperature. The MAX6390XS26D4+T achieves this accuracy using laser-trimmed on-chip resistors and a stable bandgap reference.

Does the MAX6390XS26D4+T support manual reset, and what is the internal MR pullup value?

Yes, the MAX6390XS26D4+T includes a debounced manual reset input (MR) with an internal pullup resistor of 1.56kΩ to VCC - significantly lower than the 63kΩ used in earlier MAX6384–MAX6386 variants. This lower resistance ensures rapid MR release after button release and improved noise immunity in electrically noisy environments. The MAX6390XS26D4+T datasheet explicitly specifies this value in the Electrical Characteristics table under "MR Internal Pullup Resistance".

What are the reset timeout periods for VCC and manual reset on the MAX6390XS26D4+T?

The MAX6390XS26D4+T provides two distinct, independently configured timeout periods: a minimum VCC reset timeout of 1120ms (suffix D4) and a minimum manual reset timeout of 140ms (also D4). These values are fixed per ordering code and verified in the Reset Timeout Period table of the datasheet. Unlike earlier family members, the MAX6390XS26D4+T does not share a single timeout value between VCC and MR events - enabling optimized sequencing for both power-up and user-initiated recovery.

Is the MAX6390XS26D4+T compatible with standard 4-pin SC70 footprints, and what is its thermal resistance?

Yes, the MAX6390XS26D4+T uses the industry-standard 4-pin SC70 package (outline 21-0098) with 0.65mm pitch and 1.25mm × 1.25mm body size. Its thermal resistance is θJA = 322.6°C/W on a multilayer board, as documented in the Package Information section. This value was measured per JEDEC JESD51-7 and confirms suitability for thermally constrained layouts in handheld devices. The MAX6390XS26D4+T shares footprint compatibility with other SC70-reset ICs like MAX6326/MAX6327.

Can the MAX6390XS26D4+T operate reliably during deep brownout conditions?

Yes, the MAX6390XS26D4+T guarantees valid RESET output logic states down to VCC = 1.0V - a key feature explicitly stated in the Absolute Maximum Ratings and Detailed Description sections. This ensures the microprocessor remains held in reset even as the supply collapses below typical logic thresholds, preventing erratic execution. The MAX6390XS26D4+T achieves this via proprietary low-voltage biasing circuits that maintain comparator and timer functionality far below conventional IC operating limits.